1. Field of the Invention
The present invention relates to a microscope apparatus.
This application is based on Japanese Patent Application No. 2004-330955, the content of which is incorporated herein by reference.
2. Description of Related Art
A known microscope apparatus in the conventional art is the device disclosed, for example, in Japanese Unexamined Patent Application Publication No. HEI-11-167066.
This microscope apparatus includes an objective lens having a spring-type shock-absorbing mechanism. When the tip of the objective lens is pressed by an external force, the spring-type shock-absorbing mechanism is designed to displace the tip of the objective lens in compliance with the external force. Employing such a spring-type shock-absorbing mechanism provides an advantage in that, when using an objective lens with a short working distance (WD) and the objective lens is disposed above a slide glass to examine a specimen covered with a cover glass, even if the tip of the objective lens accidentally makes contact with the cover glass, damage to the cover glass or the specimen can be avoided.
However, in the microscope apparatus disclosed in the above-cited Japanese Unexamined Patent Application Publication No. HEI-11-167066, at least one of the components of the optical system provided inside the outer barrel of the objective lens is movable in the optical axis direction with respect to the outer barrel. Therefore, if a spring-type shock-absorbing mechanism for urging the internal optical system towards the tip is also provided, the outer diameter of the entire objective lens, including the outer barrel, becomes large.
In the examination technique described in the above cited Japanese Unexamined Patent Application Publication No. HEI-11-167066, the objective lens is initially disposed outside the specimen or only the tip of the objective lens is placed in contact with the specimen. Therefore, even though the outer diameter of the entire objective lens is large, there is no problem. However, when carrying out in-vivo examination inside a living organism, such as a small laboratory animal like a mouse, it is necessary to insert the tip of the objective lens into the living organism. In such a case, if the outer diameter of the objective lens is large, it is necessary to make a large incision in the living organism, which places an excessively large strain on the living organism. Therefore, there is a drawback in that it is difficult to safely carry out in-vivo examination for an extended period of time.
Furthermore, as disclosed in the above-cited Japanese Unexamined Patent Application Publication No. HEI-11-167066, if a spring-type shock-absorbing mechanism is provided in the objective lens, when the objective lens is to be changed for another one with a different magnification, it is necessary to provide spring-type shock-absorbing mechanisms in all objective lenses, resulting in the problem of high cost.
Moreover, when a spring-type shock-absorbing mechanism is provided in the objective lens, the moving parts must have a waterproof construction, resulting in the problems of a more complex structure, larger diameter, and higher cost.